"I think I'm gonna keep bringing movie stars on book tours, because I never get this crowd!" said Jonathan Tropper, author of the 2009 New York Times best-seller, This Is Where I Leave You, at a panel discussion hosted by Plume on Friday at New York City's Javits Center, as part of Book Expo America 2014. While teasing the anticipated film adaptation alongside Tina Fey, Jason Bateman and director Shawn Levy, each of his jokes were met with loud laughter, and the book passages he read were greeted with applause before never-before-seen scenes from the Warner Bros. feature were revealed. Bateman told Tropper at one point, "Beautiful speaking voice, by the way – it's not your first barbecue, is it?"

The panel opened with Levy revealing the strategy behind the trailer, which has collected over two million YouTube views since its release on Wednesday. "We wanted a trailer that would be like the movie and the book, in that it's about people and experiences that are relatable, even though they're very specifically screwed up people," said the director, who read the book when it was first released. "It just felt so fantastically funny and poignant."

Bateman and Fey play siblings who return home to reunite with their family after their father's death, and pay respects while remaining under the same roof by sitting Shiva. Jane Fonda plays the matriarch, while Corey Stoll and Adam Driver round out the family unit. The ensemble comedy also features Dax Shepard, Rose Byrne, Kathryn Hahn, Connie Britton and Timothy Olyphant, among others.

"We're gonna play it honestly, and we're gonna worry about playing the emotions in an authentic way," said Levy of his approach. "We never felt we had to go push or go looking for the laughs. We trust that hose will come because we all work in comedy enough that we have certain instincts about that, and we played it for the reality of the feelings."

Fey noted that, because of this direction, the film can be categorized as an emotional comedy. "This is the first one, people are gonna look back at this!" she joked. "When you see it, and like the book, there are moments that are very funny and moments that, as in the book, will move you to tears…real life is never just serious. People cope through humor, so it’s a really good example, in Jonathan's writing, of an integration of real life."

Bateman said such a character is right in his wheelhouse. "If I do anything funny, it usually lives pretty close to drama anyway, I'm not a particularly skilled guy at big broad humor," he said, as he prefers to play in the middle of the two genres. "I enjoy playing characters that can do that, they can just back and forth between something humorous and something heartbreaking."

But the actor said he relished the understated comedic opportunities in the film. "There's a few jokes in the script and in the book, but he has such a confidence in his comedic sensibility that he feel she doesn't have to write a bunch of them. He creates these emotionally vulnerability situations, which is really the breeding ground of comedy anyway. There's nothing funny about someone who's bulletproof. Comedy is vulnerability, it's warts, it's dropping your pants – either on purpose or by mistake. The comedy was always right there for you to grab if you wanted to, because this story and these characters are always so raw and exposed."

This Is Where I Leave You was first optioned in 2008, and went through two other directors' hands (including Adam Shankman in 2012, with Bateman to star alongside Zac Efron, Leslie Mann, Goldie Hawn, Malin Akerman and Jason Sudeikis) before landing with Levy, who wanted to try a comedy that "pushed a little less hard." This time around, to adapt the first-person novel into a screenplay, Levy had his assistant photocopy the entire book, and underlined the specific lines he wanted Tropper to preserve. Loyalists to the novel will notice that the family surname has been swapped from Forman to Altman, due to a faint resemblance to an actual family, but they wanted the original first names to remain. "Shawn and I were just emailing back and forth vaguely Jewish names," said Tropper, who eventually chose a new surname from a list of clearances.

There are also newly-added comedic moments, such as when Wendy confronts a combative Wade (Shepard). "If you really want to insult me, say I'm too old for a center part," Fey said she told Shepard, and also added the hilarious "princess cut" line that Wendy shouts. Fey also improvised a bit during the table read, which lead to organic script changes but triggered an apology from the actress. "The way I looked at it, we were getting some free writing from Tina Fey, and I feel like whatever happens on the screen, I take credit for!" laughed Tropper.

The spine-to-screen jump also birthed a brand new scene, because producer Paula Weinstein felt that the Shiva needed more of a certain tension. "Unlike the book, Judd will be keeping the secret that his marriage is falling apart," said Tropper, who added a scene to finally spill that secret, thanks to a drunk Wendy and a frustrated Judd. It's a moment of overlapping dialogue that's mostly improvised by Fey and Bateman, as Levy gave them opposite directions, unknowingly to the other: He told Bateman, "Shut her up;" he told Fey, "Make him confess, and pull his hair hard."

The film was shot in a real house on Long Island – complete with a bedroom upstairs that was called "Actor's Clubhouse" because "our trailers were really far away," said Bateman – which happened to have the cast grow close and mirror the Shiva situation of their characters at times, as Fey recalled how Hahn and Stoll would nap in the bed together. They shot on weekends and during odd hours in order to accommodate Driver, whose Girls production schedule nearly lost him the part. "It meant seeing our families, but in the end, it was certainly worth it, because Adam Driver is Phillip," said Levy.

The panel also expanded on the preparation for the many comedic moments that center on matriarch Hillary's (Fonda) new breasts, which were enlarged for an upcoming book tour. "Early on, the day after I cast Jane, she said, 'I want to see a top prosthetician in L.A. and get really big fake bobs so we can shoot the scene where I'm in a robe, and go fully open' if I wanted to," said Levy, who joked that the "chest plate" looked completely real. "We didn't know where to look! … It's Jane Fonda below the waist and Jane Fonda above the neck … she'd flash passing-by cars in Queens – it's true! I'm not making that up!"

It's a candid off-screen Fonda moment that still fits with the character of Hillary, nevertheless. "Hillary has this shocking, traumatizing sexual candor, and Jane Fonda has a similar sexual candor that traumatized me!" Levy joked.

The panel, moderated by Entertainment Weekly senior writer and author Anthony Breznican, was the launch event of the very first BookCon. It was a homecoming for the book title, as This Is Where I Leave You first launched at BEA in 2009.